Les systèmes de support hépatique artificiels

Summary

There is no specific treatment for terminal liver failure apart from liver transplantation. Fulminant hepatitis is the most acute expression of liver failure. Transplantation for fulminant hepatitis has its limits: 15% of patients die, principally of cerebral oedema, before transplantation can be performed, and the survival rate after transplantation is lower than that after chronic liver disease, principally because of poorer patient status and emergency use of ABO-incompatible or steatotic grafts. There is therefore a need for treatment that will slow the evolution of the hepatitis and control the cerebral oedema in patients awaiting liver transplantation.

Artificial liver support systems derived from artificial kidneys have not proven suitable and bioartificial matrixes containing hepatocytes are under development. The systems under development are based upon extracorporeal circulation of the patients’s blood, or plasma, across a capillary filter containing hepatocytes in the extracapillary spaces. The hepatocytes may be human, originating from a hepatoblastoma tumour cell line, since culture of normal human hepatocytes is not yet possible, or they may be porcine. In the plasmapheresis system used at our hospital as an investigational protocol, plasma isolated from the patient is passed first across a carbon filter, and then through a capillary filter where the extracapillary spaces contain porcine hepatocytes on a matrix of dextran and collagen fibres, before being returned to the patient. In our centre, 8 patients have had 1 to 3 sessions of 6 hours each on the artificial liver while awaiting liver transplantation. Improvement in neurological status was the most significant change noted during the treatment, which was well tolerated. All patients could be transplanted; 1 died during the immediate postoperative course and another of sepsis 7 months after the operation.

In conclusion, the artificial liver support systems presently under development utilise pig hepatocytes in the extracapillary space of a semipermeable membrane. Preliminary results are encouraging, and future improvements in these systems will doubtless lead to wider applications in liver failure.